1	# ezjson: JSON for Bend 2, with a parser, a printer and a pull cursor
2	#
3	# `parse` reads text into Maybe Json. `print` writes compact text and
4	# `pretty` indented text. `cursor` reads one event at a time. Build null,
5	# booleans, numbers, strings, arrays, and objects; read them with get, at, and
6	# as_bool, as_str, as_num, as_u32, as_f32; has and len tell a missing key or
7	# index from a null; items lists an array's elements, and is_arr and is_obj
8	# tell the containers apart.
9	import Base
10	import ./src/value.bend as Value
11	import ./src/parse.bend as Parse
12	import ./src/print.bend as Print
13	import ./src/pull.bend as Pull
14	import ./src/fixed.bend as Fixed
15	
16	# a text as a value, or None when it is not JSON
17	def parse(txt: String) -> Maybe<&2, Value.Json>:
18	  Parse.parse(txt)
19	
20	# a value as compact JSON
21	def print(val: Value.Json) -> String:
22	  Print.print(val)
23	
24	# a value as JSON indented two spaces a level, one element or member a line,
25	# with no newline at the end
26	def pretty(val: Value.Json) -> String:
27	  Print.pretty(val)
28	
29	# null
30	def null() -> Value.Json:
31	  Value.null()
32	
33	# a boolean
34	def bool(flag: Bool) -> Value.Json:
35	  Value.bool(flag)
36	
37	# a string
38	def str(txt: String) -> Value.Json:
39	  Value.str(txt)
40	
41	# a JSON number from its text, or null when that text is not one
42	def num(raw: String) -> Value.Json:
43	  Value.num(raw)
44	
45	# an object from pairs
46	def obj(pairs: List<&1, String & Value.Json>) -> Value.Json:
47	  Value.obj(pairs)
48	
49	# an array from a list
50	def arr(items: List<&2, Value.Json>) -> Value.Json:
51	  Value.arr(items)
52	
53	# an object's value at a key; JNull when it is not an object or has no such
54	# key
55	def get(val: Value.Json, key: String) -> Value.Json:
56	  Value.get(val, key)
57	
58	# an array's item at an index; JNull when it is not an array or has none
59	def at(val: Value.Json, idx: U32) -> Value.Json:
60	  Value.at(val, idx)
61	
62	# whether an object has a key; false when the value is not an object. Tells
63	# a missing key from a key whose value is null, which `get` does not
64	def has(val: Value.Json, key: String) -> Bool:
65	  Value.has(val, key)
66	
67	# how many elements an array, or members an object, has; 0 for anything else
68	def len(val: Value.Json) -> U32:
69	  Value.len(val)
70	
71	# an array's elements, in order; [] when the value is not an array. One
72	# walk of the array, where a loop over `at` walks it again for every index
73	def items(val: Value.Json) -> List<&2, Value.Json>:
74	  Value.items(val)
75	
76	# whether a value is an array
77	def is_arr(val: Value.Json) -> Bool:
78	  Value.is_arr(val)
79	
80	# whether a value is an object
81	def is_obj(val: Value.Json) -> Bool:
82	  Value.is_obj(val)
83	
84	# a boolean, or none when the value is not one
85	def as_bool(val: Value.Json) -> Maybe<&2, Bool>:
86	  Value.as_bool(val)
87	
88	# a string, or none when the value is not one
89	def as_str(val: Value.Json) -> Maybe<&2, String>:
90	  Value.as_str(val)
91	
92	# a number's text, or none when the value is not a number
93	def as_num(val: Value.Json) -> Maybe<&2, String>:
94	  Value.as_num(val)
95	
96	# a number's text written with `places` decimals, rounded half to even on
97	# its decimal digits (not through a binary float), as Python's `'%.Nf'`
98	# writes a value whose decimal text is exact; None when the text is not a
99	# JSON number. A `-` is kept even when the result is zero: `-0.04` to one
100	# place is `-0.0`
101	def num.fixed(raw: String, places: Nat) -> Maybe<&2, String>:
102	  Fixed.fixed(raw, places)
103	
104	# a number as a U32, or none when it is not one or does not fit
105	def as_u32(val: Value.Json) -> Maybe<&2, U32>:
106	  Value.as_u32(val)
107	
108	# a number as an F32, or none when it is not one or does not fit
109	def as_f32(val: Value.Json) -> Maybe<&2, F32>:
110	  Value.as_f32(val)
111	
112	# a cursor at the start of a JSON text. It holds the unread suffix of that
113	# text. A span event keeps its own suffix, so it stays valid after `next`
114	# moves the cursor, and it is gone when the event is dropped
115	def cursor(src: String) -> Pull.Cur:
116	  Pull.cursor(src)
117	
118	# the next event. Commas and colons are not events. After the root value,
119	# the next call is the end, or an error if another value follows
120	def next(cur: Pull.Cur) -> (Pull.Ev & Pull.Cur):
121	  Pull.next(cur)
122	
123	# drop the next value, scalar or container, without building it
124	def skip(cur: Pull.Cur) -> Pull.Cur:
125	  Pull.skip(cur)
126	
127	# the text of a string, key, or number event, copying a span. None otherwise
128	def text(ev: Pull.Ev) -> Maybe<&2, String>:
129	  Pull.text(ev)